What happened to Silver Age Superman?

Question

So back in the late eighties DC decided to reboot Superman by making him less powerful and making changes to his back story. Specifically, that he never had been Superboy, didn't meet Lex Luthor until both were adults, etc.

The character of the Silver Age Superboy was revealed to have been a creation of the Legion foe, the Time Trapper, and was killed off in a Legion of Superheroes story. Now, wait a minute. The Silver Age Superman was supposed to have been the mature version of that Superboy character and, in his mag, made frequent references to events that had occurred in either the Superboy or Adventure Comics.

But if Superboy had been killed, who was the Superman who remembered having been Superboy? Did they ever address this in-universe?

Answer 1

The answer is ... complicated.

In Crisis on Infinite Earths, a red energy wall consumed entire universes across time. In the main DC universe, this wall was seen in both the 'today' timeline and the future Legion of Superheroes timeline. In the end, a single Earth was created instead of the multiverse, with many characters gone, who never existed in the resulting timeline, including Supergirl and Superboy. The surviving versions of heroes also differed in many respects from before; e.g., Superman had never been Superboy. John Byrne's Superman reboot followed from Crisis.

The Time Trapper saved a small portion of the original main DC timeline, containing Superboy's Smallville and not much else, neither before or after Superboy's time. IIRC, we actually see this pocket universe shrinking during the story. So, even though Superboy survived for a time in this pocket, his adult version had vanished, so no paradox ensued freom him dying to save the legionnaires who had travelled to the pocket universe.

Alan Moore and Curt Swan did a story that tied up the final fate of the Silver Age Superman if his universe hadn'ty been destroyed: Whatever Happened to the Man of Tomorrow?

Answer 2

Post-Crisis, there was no Superboy. By the time of the Legion, 1000 years had altered the historical record of Superman to match Pre-Crisis continuity, including the existence of Superboy. (Our Silver Age comic books match the Legion’s distorted history.)

To manipulate the Legion, the Time Trapper created a pocket universe matching the Legion’s history, including Superboy, for them to time travel back to. This Superboy did not live to adulthood, so there was never an extra Superman.